Multi-conductor cables are widely employed in the tele-communications and data processing fields to connect different pieces of equipment in a system together, or to connect up different portions of a single piece of equipment. Typically a complete cable, or cable assembly, is made up of a length of multi-conductor cable with a multi-contact connector at each end for cooperation with mating multi-contact connectors on or in the equipment. Cable assemblies are constructed both in factories and at the point of use of the cable, and in either event must be tested to insure that no defects exist in the cable itself, in the connectors, or in the points of connection between conductors and connector contacts. The types of defects which must be found and corrected include breaks in a conductor or its contacts ("opens"), unwanted conduction paths between one conductor and another ("shorts"), and wiring of conductors to the incorrect contacts at one connector or another ("reversals"). Because of the structure of cable assemblies, and the fact that cables are typically flexed during installation (and sometimes during system usage also), shorts or opens sometimes appear only when the cable is in a certain position or configuration. These types of shorts or opens are particularly frustrating to locate, and are termed "intermittents".
Heretofore, it has been a common practice to test cable assemblies conductor-by-conductor, and to isolate defects by cumbersome and time consuming trouble-shooting methods.